A major effort within the telecommunication industry is to merge the currently disparate voice and data communication networks. Voice networks, having evolved from analog to digital, have traditionally been implemented as circuit switched systems while data networks have evolved as packet switched systems. These voice circuit switched systems tend to severely under-utilize bandwidth. Studies indicate that approximately 20% of the available bandwidth is actually utilized for a circuit switched voice telephone call. This ineffective bandwidth use is driving the industry to move voice call processing from the circuit switched network to a packet switched network. Packet switching and transmission efficiently converges voice and data onto a single network.
Telecommunications networks typically evolve from the core outward. Network cores are quickly moving from circuit switched to packet switched systems and now the edge of the network is evolving also. The trend in integrated voice and data network access is voice over digital subscriber line (VoDSL). Voice as well as data is carried over these access lines via asynchronous transfer mode (ATM) and/or Internet protocol (IP). Currently, most network operators utilize a transition network, as shown in FIG. 1, to merge digital subscriber line (DSL) subscriber service into their current networks. DSL provides unified voice and data access (data services 20, multi-service access 21, and voice services 22) at the subscriber end of the line, but transition networks must disassociate the voice and data streams for independent processing. Prior to actual processing, the voice and data streams are split onto a data network 12 and a traditional time division multiplexed (TDM) voice network 14. Data network 12 includes an access data switch 16, and voice network 14 includes class 5 and class 4 switches 17 and 18 and media gateways 19. The digital data are then transmitted to and from a packet backbone network 24, and the voice data are transmitted to and from a public switched telephone network (PSTN) 26. Due to the necessity of accommodating these transition networks, the DSL access equipment must conform to the requirements of both the packet switched and TDM circuit switched networks to which it connects. This ‘least common denominator’ approach does not effectively utilize available resources, particularly in the narrowband voice call area.